The Catalytic Mechanism of Peptidylglycine -Hydroxylating Monooxygenase Investigated by Computer Simulation
详细信息 查看全文
- 作者：Alejandro Crespo ; Marcelo A. Martí ; Adrian E. Roitberg ; L. Mario Amzel ; Darí ; o A. Estrin
- 刊名：Journal of the American Chemical Society
- 出版年：2006
- 出版时间：October 4, 2006
- 年：2006
- 卷：128
- 期：39
- 页码：12817 - 12828
- 全文大小：361K
- 年卷期：v.128,no.39(October 4, 2006)
- ISSN：1520-5126
文摘
The molecular basis of the hydroxylation reaction of the C
of a C-terminal glycine catalyzed bypeptidylglycine -hydroxylating monooxygenase (PHM) was investigated using hybrid quantum-classical(QM-MM) computational techniques. We have identified the most reactive oxygenated species and presentednew insights into the hydrogen abstraction (H-abstraction) mechanism operative in PHM. Our results suggestthat O2 binds to CuB to generate CuBII-O2
- followed by electron transfer (ET) from CuA to form CuBI-O2-.The computed potential energy profiles for the H-abstraction reaction for CuBII-O2-, CuBI-O2-, and [CuBII-OOH]+ species indicate that none of these species can be responsible for abstraction. However, the latterspecies can spontaneously form [CuBO]+2 (which consists of a two-unpaired-electrons [CuBO]+ moietyferromagneticaly coupled with a radical cation located over the three CuB ligands, in the quartet spin groundstate) by abstracting a proton from the surrounding solvent. Both this monooxygenated species and theone obtained by reduction with ascorbate, [CuBO]+, were found to be capable of carrying out theH-abstraction; however, whereas the former abstracts the hydrogen atom concertedly with almost noactivation energy, the later forms an intermediate that continues the reaction by a rebinding step. We proposethat the active species in H-abstraction in PHM is probably [CuBO]+2 because it is formed exothermicallyand can concertedly abstract the substrate HA atom with the lower overall activation energy. Interestingly,this species resembles the active oxidant in cytochrome P450 enzymes, Compound I, suggesting thatboth PHM and cytochrome P450 enzymes may carry out substrate hydroxylation by using a similarmechanism.
of a C-terminal glycine catalyzed bypeptidylglycine -hydroxylating monooxygenase (PHM) was investigated using hybrid quantum-classical(QM-MM) computational techniques. We have identified the most reactive oxygenated species and presentednew insights into the hydrogen abstraction (H-abstraction) mechanism operative in PHM. Our results suggestthat O2 binds to CuB to generate CuBII-O2- followed by electron transfer (ET) from CuA to form CuBI-O2-.The computed potential energy profiles for the H-abstraction reaction for CuBII-O2-, CuBI-O2-, and [CuBII-OOH]+ species indicate that none of these species can be responsible for abstraction. However, the latterspecies can spontaneously form [CuBO]+2 (which consists of a two-unpaired-electrons [CuBO]+ moietyferromagneticaly coupled with a radical cation located over the three CuB ligands, in the quartet spin groundstate) by abstracting a proton from the surrounding solvent. Both this monooxygenated species and theone obtained by reduction with ascorbate, [CuBO]+, were found to be capable of carrying out theH-abstraction; however, whereas the former abstracts the hydrogen atom concertedly with almost noactivation energy, the later forms an intermediate that continues the reaction by a rebinding step. We proposethat the active species in H-abstraction in PHM is probably [CuBO]+2 because it is formed exothermicallyand can concertedly abstract the substrate HA atom with the lower overall activation energy. Interestingly,this species resembles the active oxidant in cytochrome P450 enzymes, Compound I, suggesting thatboth PHM and cytochrome P450 enzymes may carry out substrate hydroxylation by using a similarmechanism.